ceph: include average/stdev r/w/m latency in mds metrics

stdev is computed in `cephfs-top` tool - clients forward
square of sums and IO count required to calculate stdev.
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/metric.c

@@ -64,31 +64,40 @@ static bool ceph_mdsc_send_metrics(struct ceph_mds_client *mdsc,
 	/* encode the read latency metric */
 	read = (struct ceph_metric_read_latency *)(cap + 1);
 	read->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_READ_LATENCY);
-	read->header.ver = 1;
+	read->header.ver = 2;
 	read->header.compat = 1;
 	read->header.data_len = cpu_to_le32(sizeof(*read) - header_len);
 	sum = m->metric[METRIC_READ].latency_sum;
 	ktime_to_ceph_timespec(&read->lat, sum);
+	ktime_to_ceph_timespec(&read->avg, m->metric[METRIC_READ].latency_avg);
+	read->sq_sum = cpu_to_le64(m->metric[METRIC_READ].latency_sq_sum);
+	read->count = cpu_to_le64(m->metric[METRIC_READ].total);
 	items++;
 
 	/* encode the write latency metric */
 	write = (struct ceph_metric_write_latency *)(read + 1);
 	write->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_WRITE_LATENCY);
-	write->header.ver = 1;
+	write->header.ver = 2;
 	write->header.compat = 1;
 	write->header.data_len = cpu_to_le32(sizeof(*write) - header_len);
 	sum = m->metric[METRIC_WRITE].latency_sum;
 	ktime_to_ceph_timespec(&write->lat, sum);
+	ktime_to_ceph_timespec(&write->avg, m->metric[METRIC_WRITE].latency_avg);
+	write->sq_sum = cpu_to_le64(m->metric[METRIC_WRITE].latency_sq_sum);
+	write->count = cpu_to_le64(m->metric[METRIC_WRITE].total);
 	items++;
 
 	/* encode the metadata latency metric */
 	meta = (struct ceph_metric_metadata_latency *)(write + 1);
 	meta->header.type = cpu_to_le32(CLIENT_METRIC_TYPE_METADATA_LATENCY);
-	meta->header.ver = 1;
+	meta->header.ver = 2;
 	meta->header.compat = 1;
 	meta->header.data_len = cpu_to_le32(sizeof(*meta) - header_len);
 	sum = m->metric[METRIC_METADATA].latency_sum;
 	ktime_to_ceph_timespec(&meta->lat, sum);
+	ktime_to_ceph_timespec(&meta->avg, m->metric[METRIC_METADATA].latency_avg);
+	meta->sq_sum = cpu_to_le64(m->metric[METRIC_METADATA].latency_sq_sum);
+	meta->count = cpu_to_le64(m->metric[METRIC_METADATA].total);
 	items++;
 
 	/* encode the dentry lease metric */

fs/ceph/metric.h

@@ -19,8 +19,14 @@ enum ceph_metric_type {
 	CLIENT_METRIC_TYPE_OPENED_INODES,
 	CLIENT_METRIC_TYPE_READ_IO_SIZES,
 	CLIENT_METRIC_TYPE_WRITE_IO_SIZES,
-
-	CLIENT_METRIC_TYPE_MAX = CLIENT_METRIC_TYPE_WRITE_IO_SIZES,
+	CLIENT_METRIC_TYPE_AVG_READ_LATENCY,
+	CLIENT_METRIC_TYPE_STDEV_READ_LATENCY,
+	CLIENT_METRIC_TYPE_AVG_WRITE_LATENCY,
+	CLIENT_METRIC_TYPE_STDEV_WRITE_LATENCY,
+	CLIENT_METRIC_TYPE_AVG_METADATA_LATENCY,
+	CLIENT_METRIC_TYPE_STDEV_METADATA_LATENCY,
+
+	CLIENT_METRIC_TYPE_MAX = CLIENT_METRIC_TYPE_STDEV_METADATA_LATENCY,
 };
 
 /*
@@ -38,6 +44,12 @@ enum ceph_metric_type {
 	CLIENT_METRIC_TYPE_OPENED_INODES,	   \
 	CLIENT_METRIC_TYPE_READ_IO_SIZES,	   \
 	CLIENT_METRIC_TYPE_WRITE_IO_SIZES,	   \
+	CLIENT_METRIC_TYPE_AVG_READ_LATENCY,	   \
+	CLIENT_METRIC_TYPE_STDEV_READ_LATENCY,	   \
+	CLIENT_METRIC_TYPE_AVG_WRITE_LATENCY,	   \
+	CLIENT_METRIC_TYPE_STDEV_WRITE_LATENCY,	   \
+	CLIENT_METRIC_TYPE_AVG_METADATA_LATENCY,   \
+	CLIENT_METRIC_TYPE_STDEV_METADATA_LATENCY, \
 						   \
 	CLIENT_METRIC_TYPE_MAX,			   \
 }
@@ -61,18 +73,27 @@ struct ceph_metric_cap {
 struct ceph_metric_read_latency {
 	struct ceph_metric_header header;
 	struct ceph_timespec lat;
+	struct ceph_timespec avg;
+	__le64 sq_sum;
+	__le64 count;
 } __packed;
 
 /* metric write latency header */
 struct ceph_metric_write_latency {
 	struct ceph_metric_header header;
 	struct ceph_timespec lat;
+	struct ceph_timespec avg;
+	__le64 sq_sum;
+	__le64 count;
 } __packed;
 
 /* metric metadata latency header */
 struct ceph_metric_metadata_latency {
 	struct ceph_metric_header header;
 	struct ceph_timespec lat;
+	struct ceph_timespec avg;
+	__le64 sq_sum;
+	__le64 count;
 } __packed;
 
 /* metric dentry lease header */